Selection mechanism



Jan. 22, 1952 G. K HURNI I 2,583,377

SELECTION MECHANISM Filed March 17, 1947 INVENTOR; George A. Hu/"n/ Patented Jan. 22, 1952 SELECTION MECHANISM George K. Hurni, Oakland, Calif., assignor to Marchant Calculating Machine Company, a corporation of California Application March 17, 1947, Serial No. 7 35,053

nism itself; and much effort has been directed toward such: improvement.-. However, changes of anaobvious nature. such=as decreasing the force.

exerted by the springs which tend to hold the keys, raised position to thereby make them emierrto depress; all introduce difliculties which limit: the extent:to which the key touch can be lightened by suchexpedients or else require the addition of .special. mechanism for overcoming the diflicultiesintroduced, thus making the mechanism very complex;

It .is the primaryv obiectof the present invention to lighten thekey touch of the keys of flexibIe keyboardswithout impairing any operational featuresrthereof and'without the introduction of mechanical: complications.

Flexible keyboards generally include a series of banks of springraised depressible keys; usually nine in abank, and-a keylatching member associated witheach. bank of keys in sucha way as tmbewcapable-ofplatching any key in the bankin depressedrposition; but: operable by any other key ms.the..bank,..upon: depression thereof, ,to release the :previouslyLdepressed key. and latch down the second key. Preferably each bank of keysis also provided. withv interlocks effective to prevent simultaneous. depression of two or more keys to latched? position. The part of thevalue entering mechanism. set :by the depressible' keys commonly, but not necessarily,v includes what is known as aV-slotzbanhavingxcam edged notches one of .which is engaged by each key so that depression of a givenkeywill move the bar a distance proportionate to r the key value.

Thepresentinventionis based upon the principle-1.01 imposing'upon certain of these conventional elementsof a'flexiblekeyboard, additional functions of such a character as to permit the lightening-of the. key springs and,-optionally, the adoption of other'expedients for lightening the key touch, without introducing operational difficulties such as would otherwise'result from the adoption of such expedients:

lh orderto"illustrate the extent to whichthe 2 advantages may be realized by the application of this principle according to the present invention, it is disclosed herein as embodied in the commercially known Marchant calculatingmachine as shown and described in the Avery Patent N0. 2,271,240, but while this disclosure illustrates the preferred mode of applying the principle outlined above, it will be understood that the invention is applicable as well to any key-setmachine embedying a flexible keyboard.

Additional objects and advantages of the invention willalso be apparent from the following description, reference being had'to the accom panying drawings, in which:

Figure 1 is a right side view of-one denominational order of the keyboard and selection mechanism of a Merchant calculating machine embodying the present invention.

Figure'Z is a sectional view taken on the line 2-2 of Figure 1.

Figure 3 is an enlarged fragmentary view of part of the mechanism of Figure 1, showing the number one key depressed and latched and the number nine key in normal raised position.

When a numeral key is depressed it sets or conditions selection mechanism prior to entry of a value into the accomulator by the actuator. In

the case of the machine in connection with which the present invention is disclosed, the keys in a given order each efiect movement of a difieren-j tiallysettable selection bar in predetermined amounts depending on which numeral key is de-" pressed. Each selection bar rotates a segment I32 counterclockwise. The-segment, in turn, sets arelated selection unit [46in accordance with the key depressed and also rotates a numeral wheel I40 to indicate the numeral value of the key depressed. The numeral key, sections are provided with latch barsv ill to hold a key in depressed position,arranged so that the depression of anynumeral key will cause the bar Ill to release any previously depressed key in that order. n n

More specifically, the'keyboard mechanism disclosed for effecting the above operations includes a'series of nine keys' I00 (Figs. 1, 2, and 3) eachof which is mounted forupgand down movement in aframe lfll andis urged upwardly by a spring.

I02 as disclosed in Avery Patent No. 2,271,240.-

In the machine of the'present invention the key touch is lightened by making these springs of the minimum strength necessary to raise a respective key and tohold-the same in itsnormal raised position. In order to insure the prompt rise of a depressed key upon depression of another key in that same order (previously accomplished by springs I02, which had therefore to be made substantially stronger) the weaker spring is supplemented by utilizing the force of the depression of the key to positively raise a previously depressed key. This function is accomplished by means which also serves as an interlock between the keys so as to prevent two keys from being locked down either by such simultaneous depression or by rapid sequential depression of two keys.

This interlocking and key-raising means comprises a series of bellcrank levers 20, each of which is freely mounted on the frame IOI by a stud 25 and so related to the next adjacent bellcrank that clockwise rotation of any one of them about its pivot will cause all bellcranks 20 to its left as viewed in Figure l, to rotate clockwise equal amounts about their respective pivots;

conversely, if any bellcrank 20 be rotated counterclockwise, all bellcranks 20 to its right will be rotated counterclockwise an equal amount.

An extension II (Figs. 1 and 2) is provided on each of the key stems I03, which extension is adapted to cooperate with a shoulder 23 of one bellcrank 20 and shoulder 24 of an adjacent bellcrank 20. Thus, when a key I00 is depressed, extension II of stem I03 contacts shoulders 23 and 24 of two adjacent bellcranks 20, rotating one bellcrank counterclockwise and the other clockwise respectively, and each one of the two bellcranks so rotated exerts a similar motion to the adjacent bellcrank 20 to the right or left respectively by means of a radial heel 2| or toe 22, each of which cams its adjacent toe 22 or heel III. The bellcranks initially rotated act upon the adjacent ones and so on throughout the series; the series in effect acting simultaneously.

Those bellcranks wh ch are rotated clockwise raise their shoulders 23 under the extensions I I of the key stems I03, and those which are rotated counterclockwise raise their shoulder 24 under the respective extensions II. In either case the shoulders 23 and 24 will force up any previously depressed key, locking it and all keys except the one being depressed, in normal raised position.

Disposed beneath the numeral keys I00 in each bank or order is a differentially settable selection bar (Figs. 1, 2, and 3) which is suspended from channel frame IOI by means of two parallel links I28 and I29, freely pivoted on studs in the frame IOI, thus permitting endwise movement of the bar 30. This bar has nine V-shaped recesses, each of which terminates in a notch I3I proportioned to receive the end I2 (Figs. 2 and 3) of an associated key stem I03 so that the bar 30 will be accurately positioned. The key stems I03 are spaced equal distances apart, and these distances are slightly greater than the spacing between successive notches I3I, so that each succeeding notch will be spaced one increment farther away from its cooperating key stem. Depression of a numeral key will therefore cam the selection bar 30 to the right a number of increments proportional to the value represented by the depressed key. The greater the value of the key depressed, the greater the number of increments the bar will be displaced from normal position. A spring I64 (Fig. 1) attached to segment I32 and suitably anchored to a part of the machine normally urges the selection bar 30 to the left which is the normal position of the bar, and which direction is opposite to that in which the bar is advanced by the keys.

Each key stem I03 also has a cam extrusion IIB (Fig. 3) which, upon depression of the associated key, cams a slotted key locking slide II'I toward the right as viewed in Figs. 1 and 3. This locking slide is supported for sliding movement on the bottom flange of channel frame IOI by studs fixed to the slide and extending through elongated holes in the frame. When a numeral key stem has been depressed the cam extrusion II6 passes beneath the slide and permits the latter to return to its initial position under urge of a spring I I8, and by overlying the upper end of the extrusion IIG the slide latches the depressed key in its depressed position. The setting of any value in a keyboard order can be changed simply by depressing a difierent key in the same order. The depression of the second key cams the looking slide toward the right as described above and at approximately the mid-point of key depression the extrusion releases the key which was previously depressed and latched down.

Because of the provision for rapidly and surely raising a key by means of the previously described key raising means, it is possible according to the present invention to form the extrusion IIB so that the greatest width of the extrusion at point N (Fig. 3) is closer to the shoulder I8 than according to prior designs. duced camming angle to face I9 and consequently lightens the key touch by easing the resistance of latch bar II'I against the key without lengthening the total stroke of the key, and also permits deeper depression of a key before a previously depressed key is released, thereby providing greater safetyagainst inadvertent release of a depressed key by an accidental light depression of another key. But for the action of the positive key-raising means of the present invention, a steeper camming angle on face I9 would be necessary in order to enable even a heavier key spring to raise a depressed key clear of its notch I3I in the selection bar 30 before movement of said bar by depression of a second key in an interchange of setting keys in which one depressed key is released by depression of another.

Because of the provision for rapidly and positively raising a key by means of the previously described key raising means, it is also possible according to the present invention, to further lighten the key touch by making the camming surfaces of the V-shaped recesses in bar 30 somewhat steeper than in prior designs, without risk that one depressed key will not rise clear of its notch I3I before a second key engages the bar 30. In the illustrated embodiment of the invention,

in order to provide for easier setting of the selec-'.

tion mechanism by the keys I00, the camming angles of bar 30 have been made steeper by various amounts. With the exception of the camming angles underlying the number one, two, and three keys, this variation has been chosen so as to give the most favorable angles to those cammin surfaces which, when moved by the keys, set the selection bar the greater number of increments from normal position. The camming angles underlying the one, two, and three.

keys on the other hand are given a less favorable angle in order to keep the key touch of those keys approximately the same as that of the higher value keys.

The steepening of the camming angles by the,

maximum amounts permitted by the key raising mechanism, however, presents certain added problems. When the displacement of the selection bar must be maintained the same as that attained by the prior mechanism of the afore- This gives a rementioned patent, and the key notches I 3| in bar 30 are equally spaced, 1 any variation in the anglesof, the' camming. surfaces 3| requires that some of the latter be of different heights. Thus, in the presentembodiment. the cam surfaces which act in moving the selection bar 30 the greatest amounts are increased in height and very. closely. to. the bottom ofv the key stems.

"The increased .heightand thevariations in the-heights' o'fthe cam surfaces createsa problemiof clearance between the selection bar and adepressed key vvhen..a..second key is depressed. Fbriexample'; ,assumethat. with either the; number one or number two key latched down with the bottom of the stem in its notch l3l, the number nine key be depressed. The latter key normally lies closer to the selection bar than does any other key. This is because the nine key must displace the bar a greater number of increments than any other key. Thus, if the nine key were depressed it would almost immediately engage its cooperating camming surface of bar 30 and start to move the bar before the locking slide I ll could release either the number one or number two key. Consequently, a bind would exist between the number one or two ke and the nine key through the selection bar. Similar binds would be possible between the one key and the six, seven, or eight keys, but the one and nine keys are referred to hereinafter as typically illustrating the example of interference.

The selection bar of the machine of the present invention is proportioned in the following manner so as to prevent the above mentioned interference. When the #1 key I (Fig. 3) is depresssed the lower edge of the key stem engages a primary camming surface 31 and moves the selection bar one increment toward the right as described hereinbefore and then the bottom of the key stem moves down into the notch to the position shown by the dotted line numbered 34 to thereby positively locate the bar and prevent overthrow. When the operator releases the key, the spring |02 raises the key to the full line position of the end I2 shown in Fig. 3 where it is retained by the lock bar Ill. The spring I64 (Fig. 1) urges the bar toward the left but such retrograde movement is blocked by the shoulder 38 pressing against the side of the key stem which thereafter holds the bar in the #1 position shown. In rising to the locked position shown in Fig. 3, however, the bottom of the key stem moves above and out of engagement with shoulder 39 since the latter shoulder has no part in maintaining the bar set once it is positioned.

Assuming now that the #9 key is depressed, the bottom of the nine key stem almost immediately engages the camming surface 3| and starts to move the bar before the extrusion H6 of the #9 key moves down far enough to release the #1 key from the lock bar I II in a manner described hereinbefore. If the shoulder 39 for the #1 notch were at the same level as the shoulder 38 as shown in Avery Patent No. 2,271,240, the shoulder 39 to the left of the #1 key stem would block the immediate rightward movement of the selection bar and thus prevent depression of the nine key; and the pressure of the nine key against the selection bar and the consequent pressure of the left shoulder against the side of the #1 key stem would prevent the release of the #1 key. even if the #9 key could be forced low enough to release the latch bar, such as by a slow depression of the nine key. Since the shoulder 39 and its. adjacent secondary camsurs face 42 are lowered.,however,. as in the case of the nine key, and the #1 key will be free to rise when the #9 key releases. the ,same fromthe lock bar I IT. The foregoing ar angement, there-, fore, provides for positiveapositioning of the selection bar by the #1 key with means for re taining the bar in the #1 position, but at the same time permits the movement of the. bar toward the #9 position before the #1 key is released by the nine key. The left shoulder ll of the number twonotch l3l is cut away similar to that of the number one notch in order to prevent a bind between the number nine key and the number two key as explained hereinbefore.

There can be no interference between any combination of the keys other than the ones described above because in all other cases the locking slide l I! effects release of a key before a depressed key can start to move selection bar 30, and if that part of the lightening of the key touch achieved by changing the camming angles of the selection bar is not desired to be availed of to the maximum extent, the shoulders 39 and 4| need not be made lower than their opposite shoulders; this being an optional feature of the invention.

The present invention therefore overcomes'all objections inherent in lightening the key springs I02 and in giving the cam surfaces of the selection bar 30 and of the extrusions H6 more favorable camming angles.

I claim:

In a calculating machine having a keyboard comprising a series of depressible keys representative of the numeral values 1 to 9 respectively, each key including a key stem guided for up and down movement in the frame of the machine and manipulable from a normal to a fully depressed position, and a device effective upon manual depression of one of said keys for latching the same in an intermediate position substantially above the fully depressed position and effective upon depression of another key of said series for releasing the first key from restraint of said device and for latching said other key in depressed position; the combination of, a differentially settable bar mounted for movement to a plurality of positions each corresponding to the respective value of a depressed key, said bar including a plurality of recesses each composed of a primary camming surface which is engaged by the stem of a key of greater value than the first one depressed to advance the bar to a position corre-- sponding to the second key depressed and a secondary camming surface which is engaged by the key stem of a key of lesser numeral value than the first one depressed to move the bar in the reverse direction to the position corresponding to the second key depressed, the slope of the secondary camming surface for the lesser value key being substantially less than the slope of the primary camming surface for the greater value key to permit the releasing means to release said greater value key from said latching device upon depression of the lesser value key before the latter engages its secondary camming surface, and a notch composed of two oppositely disposed shoulders at the bottom of the primary and secondary camming surfaces respectively which shoulders embrace the bottom of the key stem to positively locate the bar in the position corresponding to the key depressed, the shoulders of the notch 'for a lesser value key being of such heights with respect to each other that when REFERENCES CITED said key is latched in said intermediate position The following references are of record in the bg said device the bottom of its key stem is in file of this patent:

t e path of the shoulder at the bottom of the 5 respective primary camming surface but is above UNITED STATES PATENTS and-out of the path of the shoulder at the bot- Number Name Date tom of the respective secondary camming sur- 1,044,020 Clement 12, 1912 face to thereby permit the movement of the bar 2,043,021 c J1me 1936 in response to depression of a greater value key ,0 ,6 COODBI y 1937 while the lesser value key is latched in its inter- ,2 3 T lrc 8b a D 1940 mediate position. 2,279,456 Friden et a1 Apr. 14, 1942 2,294,948 Avery Sept. 8, 1942 GEORGE K. HURNI. 2,391,089 Friden et al Dec. 18, 1945 

